Film Facts 2: Gravity Capsule

Gravity was pretty good, wasn't it? Yeah, it's pretty much unanimous that it was a great film, with some stellar (eh, eh?!) acting from Sandra "Hyperventilating" Bullock and George Clooney and very pretty CGI and sound editing; I'll be gobsmacked if it doesn't pick up this year's Academy Award for visual effects, which it's apparently already in the finalists for. Since we all already know Gravity is good, I thought I'd skip the whole reviewing thing and focus on some of the logistics of the movie. Heads up to those of you that still think Hollywood has the balls to hire someone like Sandra Bullock and kill her off, because I'm going to spoil the ending for you. Around about...now.

Space never looked so dirty.

She lives. Shock, horror. But, frankly, that's hardly the point of the film and if this truly ground-breaking revelation is going to detract from your enjoyment the I shall gleefully direct you to this Cracked article (which is, obviously, gospel) that says you apparently enjoy things more when you already know the end. So mneh.

I'm right, you're wrong. I'm big, you're small. I'm...I forget...

At the end of the movie, Bullock's capsule lands in some unnamed lake and she stumbles onto the shore to the sound of epically dramatic tribal music because this movie is so tentative with it's imagery of rebirth that it pretty much just goes full on Lion King on our asses for the finale. Hell, it would have been subtler to just steal that shot of the starchild from the end of 2001 and be done with it.

"Now how did that get there...?" - Alfonso Cuarón 

This whole not criticising a film thing is harder than it looks. Anyway, why don't we have a look at the statistical possibilities of landing in such a place, shall we? If you're at all like me, you might remember xkcd's What If column covering the relatively similar topic of the likelihood of finding signs of intelligent life anywhere on the planet, but his statistics (other than the typical "70% of the planet is water" one) are of very little use here. If we start with our target destination then: IMDb says that the location for the landing scene was at Lake Powell in Arizona. A quick Google map of the lake shows that it's actually just over the state line into Utah, but we're just getting niggly here. This totally legitimate source suggests that a more specific shooting locating was in a shallow bay just south of Lake Powell, which is entirely likely seeing as the geography of the final product has been changed completely in post production so we'll take that as our starting block.

Movie (above) and Google Maps (below), both facing in approximately the same direction.

A cursory glance (you can always trust me for the most painstakingly accurate measurements) at the scale bar on the map tells me that the bay is about 200x300m-ish exactly, so Sandra hit a 60'000 square metre, or 0.06 square kilometre, pool of water with her capsule, about the same size as three standard international 105x68m football pitches. If we take that at face value and look at the same area in comparison with the 510'072'000 square kilometre area of the Earth, that makes up just under 0.0000000118% of the total surface of the Earth, or the other way round you could fit the bay onto the face of the Earth 8 and a half billion times. How fascinating. However, none of these numbers are actually getting us anywhere, so let's get down to brass tacks.

"Have you even started yet?"

I'm sure we've all heard before that around about 70% of the Earth's surface is water (the most exact percentage I could find was a Wiki Answers with 71.13%), so the simplest statistic for us to start with is that, obviously, there was a 71% chance of Sandra landing on water; soggy planet for the win.

"I'm so wet..." - Earth

But wait! Although it's never indicated in Gravity when the events of the film take place and we're meant to assume it is in present day, the more accurate date of space explosion smashy smashy is around the year 2022. Why, you ask? Well, the Chinese space station that Sandra Bullock's character finds herself in after ISS is torn to shreds is based on a real-life station called Tiangong-1. At the moment, Tiangong looks nothing like it does in the film, only being made up of one shuttle, but the plan is to slowly build up to a science laboratory by 2020-2022, the finished product of which we get the joy to see getting torn to shreds in glorious high definition; thus 2022 being a better choice of setting for the movie. As we all know, the sea levels are slowly rising, so there'll be a little more water in ten years than there is now. At 3.2mm per year, the sea levels will have risen a staggering 25.6mm, or the height of three and a half iPad Airs. So essentially you could stack four iPads by the ocean and Apple will have installed iOS into your eyeballs before the top one gets wet. That's a fancy way of saying that this consideration is negligible and I've wasted a paragraph of everybody's time.

But you need never worry about leaving your iPad at the beach ever again.

Sandra didn't land in the ocean though, did she. The coastal zone is the name given to that shallow bit of the ocean that keeps rubbing up against the land like a really creepy uncle and is defined as bits of the ocean under a depth of 200m, which in total cover around about 26'000'000 square kilometres of the Earth's surface. Rivers and lakes (those that were big enough to be measured) make up about another 1.5 million square kilometres; that means the likelihood of landing on the coast or in a lake or river like what happens in the film is 5.39%, which is about the same as having a genetic disorder of some kind. The lesson here: don't try to pilot a space capsule into a lake if you have coeliac disease.

Any space landing is pretty hard to stomach. Doctor joke!

Of course, space stations and satellites follow very specific orbits, meaning there are parts of the Earth more or less likely to be landed on depending on where your orbit happens to be. As this handy teaching aid informs us, imaging satellites usually orbit north to south over the poles while space stations like the ISS and Tiangong orbit laterally (follow the hyperlinks to see live orbit trackers); as such we can pretty much ignore anything that's not underneath the flightpath of Tiangong, which we'll have to assume won't have changed much in the next 10 years. Sadly I can't seem to find anything that gives me a good indication of how far from under it's orbit a shuttle can stray during re-entry so I'm going to be super ignorant and say they don't; shuttles go straight down.

So says science. Well, me, but also science.

As such, looking at the orbit of Tiangong we can pretty much ignore Russia, Canada, Greenland, Antarctica and the North Pole along with a good chunk of the South Atlantic, Pacific most of the Southern Ocean (something I didn't actually know existed until about now) and all of the Arctic Ocean. Excuse me while I maths for a second and work out the area of a planet with it's top and bottom shaved off. Some. There is some Earth left. And by subtracting these land masses and oceans from the total area of the Earth and redoing the ratio, the chances of Tiangong hitting water is 3 in 4, or a 75% chance. That's better odds than that thing with the doors and the goats.

If you did get a goat, don't let it pilot the shuttle.

All in all, to wrap up this series of rather disappointing facts, the likelihood of Sandra's capsule landing on water and not smashing her into the ground like a tin can full of delicious space Spam is in her favour, but the chances of her landing in waist deep water on a river within walking distance of a city are silly levels of unlikely. I guess I could have saved us all a lot of time by just writing that one sentence. You're welcome. I'm keeping the goat.